Silicon carbide powder, method for manufacturing silicon carbide ingot using the same, and silicon carbide wafer

ABSTRACT

Disclosed are a silicon carbide powder, a method of manufacturing a silicon carbide powder, and a silicon carbide wafer. More particularly, the silicon carbide powder includes carbon and silicon and in the silicon carbide powder, O1s/C1s of a surface measured by X-ray photoelectron spectroscopy is 0.28 or less.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit of priority to Korean Patent ApplicationNo. 10-2021-0186627 filed on Dec. 23, 2021 in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

An embodiment relates to a silicon carbide powder, a method ofmanufacturing a silicon carbide ingot, and a silicon carbide wafer.

BACKGROUND ART

Silicon carbide (SiC) has excellent heat resistance and mechanicalstrength, has strong radiation-resistant properties, and is advantageousin that it can be used to manufacture in a large-diameter substrate. Inaddition, silicon carbide has excellent physical strength and chemicalresistance, a large energy band gap, and a larger electron saturationdrift rate and withstand pressure. Therefore, it is widely used forabrasives, bearings, fireproof plates, etc. as well as semiconductordevices requiring high power, high efficiency, high-pressure resistance,and large capacity.

Silicon carbide is manufactured by various methods such as heattreatment or energization of carbon raw materials such as siliconcarbide waste. As conventional methods, there are the Acheson method, areaction sintering method, an atmospheric pressure sintering method, achemical vapor deposition (CVD) method, and the like. However, thesemethods have a problem in that carbon raw materials remain, and aredisadvantageous in that these residues act as impurities, which candeteriorate the thermal, electrical, and mechanical properties ofsilicon carbide.

For example, Japanese Patent Application Publication No. 2002-326876discloses a method of reacting a silicon carbide precursor, which hasundergone a heat treatment process, at a high temperature under thecondition of an inert gas such as argon (Ar) so as to polymerize orcross-link a silicon source and a carbon source. However, such a processhas problems in that the manufacturing cost is high and the size of apowder is not uniform because heat treatment is performed at a hightemperature of 1,800° C. to 2,100° C. under vacuum or inert gasconditions.

Moreover, wafers used in the solar cell and semiconductor industries aremanufactured by growing from a silicon ingot in a crucible made ofgraphite or the like, and in this manufacturing process, not only wasteslurry containing silicon carbide, but also silicon carbide wasteadsorbed on the inner wall of the crucible is generated in a significantamount. Until now, such wastes have been disposed of in landfills,causing environmental problems and resulting in high disposal costs.

DISCLOSURE Technical Problem

Therefore, the present invention has been made in view of the aboveproblems, and it is one object of the present invention to provide asilicon carbide powder having improved purity and a low surface oxygencontent, a method of manufacturing a silicon carbide ingot using thesilicon carbide powder, and a silicon carbide wafer with improvedperformance.

In accordance with an aspect of the present invention, the above andother objects can be accomplished by the provision of a silicon carbidepowder including carbon and silicon, wherein O1s/C1s measured by X-rayphotoelectron spectroscopy is 0.28 or less.

In the silicon carbide powder according to one embodiment, O1s/Si2p of asurface measured by X-ray photoelectron spectroscopy may be 0.39 orless.

In the silicon carbide powder according to one embodiment, an oxygenratio in the surface measured by X-ray photoelectron spectroscopy may be13 atom % or less.

In the silicon carbide powder according to one embodiment, N1s/C1s ofthe surface measured by X-ray photoelectron spectroscopy may be 0.018 orless.

In the silicon carbide powder according to one embodiment, aconcentration of oxygen in a depth where an oxygen concentration changeaccording to an etching time is 2 atom %/100s or less may be 5 atom % orless.

In the silicon carbide powder according to one embodiment, Zn2p/C1s of asurface of measured by X-ray photoelectron spectroscopy may be 0.023 orless.

In the silicon carbide powder according to one embodiment, Mg1s/C1s ofthe surface of the silicon carbide powder measured by X-rayphotoelectron spectroscopy may be 0.005 or less.

In accordance with another aspect of the present invention, there isprovided a method of manufacturing a silicon carbide powder, the methodincluding: providing a raw material containing silicon carbide;pulverizing the raw material; and removing an impurity included in theraw material, wherein Ols/Cls of a surface measured by X-rayphotoelectron spectroscopy is 0.28 or less.

In the method of manufacturing a silicon carbide powder according to oneembodiment, the removing may include etching a surface of the rawmaterial.

In the method of manufacturing a silicon carbide powder according to oneembodiment, an etchant including hydrofluoric acid and nitric acid maybe used in the etching.

In accordance with yet another aspect of the present invention, there isprovided a silicon carbide wafer, including a Si surface and C surfaceopposite to each other, wherein a ratio of oxygen measured by X-rayphotoelectron spectroscopy in the Si surface is 14 atom % or less.

Advantageous Effects

In a surface of a silicon carbide powder according to an embodiment,carbon and oxygen are included in an appropriate content ratio.Accordingly, when a silicon carbide ingot and a silicon carbide wafer ismanufactured using the silicon carbide powder according to anembodiment, the content of the oxygen is appropriate, so that defects ofthe silicon carbide ingot and the silicon carbide wafer can be reduced.

In particular, since carbon and oxygen are included in an appropriatecontent ratio in the surface of the silicon carbide powder, the oxygencan be easily removed through reaction with the carbon in an initialheat treatment step. Accordingly, oxygen in the surface of the siliconcarbide powder can be removed in the initial heat treatment process, anddefects in a process of growing the silicon carbide ingot can beminimized.

In addition, the oxygen is removed in the form of carbon dioxide byreacting with the carbon, and in the process of removing the oxygen, theconsumption of the carbon can be reduced. Accordingly, even after theoxygen is removed together with the carbon, the ratio of the silicon andthe carbon can be appropriate over an entirety of the silicon carbidepowder. Accordingly, the silicon carbide powder according to anembodiment can minimize defects that may occur due to non-uniformcontent of the carbon and the silicon.

In addition, the silicon carbide powder according to an embodimentincludes silicon and oxygen in an appropriate content ratio on thesurface thereof. Accordingly, the silicon carbide powder according to anembodiment can be effectively protected from external impurities. Thatis, the silicon carbide powder according to an embodiment can include anoxygen-containing protective film on the surface thereof and can beeffectively protected from external chemical impact.

By using the silicon carbide powder according to an embodiment, asilicon carbide wafer with improved performance can be manufactured.

DESCRIPTION OF DRAWINGS

FIG. 1 is a flowchart illustrating a process of manufacturing a siliconcarbide powder according to one embodiment.

FIG. 2 is a flowchart illustrating a process of manufacturing a siliconcarbide powder according to one embodiment.

FIG. 3 is a flowchart illustrating a process of manufacturing a siliconcarbide powder according to one embodiment.

FIG. 4 is a flowchart illustrating a process of manufacturing a siliconcarbide powder according to one embodiment.

FIG. 5 is a flowchart illustrating a process of manufacturing a siliconcarbide powder according to one embodiment.

FIG. 6 is a flowchart illustrating a process of manufacturing a siliconcarbide powder according to one embodiment.

FIG. 7 is a sectional view illustrating a process of growing a siliconcarbide ingot.

FIG. 8 is a graph illustrating element contents in a surface of asilicon carbide powder, manufactured according to Example 1, measured byX-ray spectroscopy.

FIG. 9 is a graph illustrating element contents in a surface of asilicon carbide powder, manufactured according to Example 2, measured byX-ray spectroscopy.

FIG. 10 is a graph illustrating element contents in a surface of asilicon carbide powder, manufactured according to Comparative Example 1,measured by X-ray spectroscopy.

FIG. 11 is a graph illustrating element contents in a surface of asilicon carbide powder, manufactured according to Comparative Example 2,measured by X-ray spectroscopy.

FIG. 12 is a graph illustrating element contents in a silicon carbidepowder, manufactured according to Example 1, measured by X-rayspectroscopy according to an etching time.

FIG. 13 is a graph illustrating element contents in a silicon carbidepowder, manufactured according to Example 2, measured by X-rayspectroscopy according to an etching time.

FIG. 14 is a graph illustrating element contents in a silicon carbidepowder, manufactured according to Comparative Example 1, measured byX-ray spectroscopy according to an etching time.

FIG. 15 is a graph illustrating element contents in a silicon carbidepowder, manufactured according to Comparative Example 2, measured byX-ray spectroscopy according to an etching time.

BEST MODE

Hereinafter, the invention will be described in detail throughembodiments. The embodiments are not limited to contents disclosed belowand may be modified in various forms so long as the gist of theinvention is not changed.

In the present specification, when a part “comprises” a certaincomponent, it means that other components may be further comprised,rather than excluding other components, unless otherwise specified.

It should be understood that all numbers and expressions indicating theamounts of components, reaction conditions, etc. described in thisspecification are modified by the term “about” in all cases unlessotherwise specified.

First, a method of manufacturing a silicon carbide powder according toan embodiment includes a step of preparing a silicon carbide rawmaterial.

The silicon carbide raw material includes silicon carbide. The siliconcarbide raw material may include α-phase silicon carbide and/or β-phasesilicon carbide. In addition, the silicon carbide raw material mayinclude a silicon carbide monocrystal and/or a silicon carbide polycrystal.

In addition, the silicon carbide raw material may further includeunwanted impurities in addition to silicon carbide.

The silicon carbide raw material may further include a carbon-basedmaterial such as graphite as an impurity. The carbon-based material maybe derived from a graphite crucible and the like. The carbon-basedmaterial may include the silicon carbide raw material in a content ofabout 5% by weight to about 50% by weight. The carbon-based material maybe included in a content of about 50% by weight or less in the siliconcarbide raw material. The carbon-based material may be included in acontent of about 45% by weight or less in the silicon carbide rawmaterial. The carbon-based material may be included in a content ofabout 40% by weight or less in the silicon carbide raw material. Thecarbon-based material may be included in a content of about 1% by weightto about 50% by weight in the silicon carbide raw material. Thecarbon-based material may be included in a content of about 5% by weightto about 45% by weight in the silicon carbide raw material. Thecarbon-based material may be included in a content of about 10% byweight to about 40% by weight in the silicon carbide raw material. Thecarbon-based material may be included in a content of about 10% byweight to about 35% by weight in the silicon carbide raw material. Thecarbon-based material may be included in a content of about 10% byweight to about 30% by weight in the silicon carbide raw material. Thecarbon-based material may be included in a content of about 10% byweight to about 20% by weight in the silicon carbide raw material.

The silicon carbide raw material may further include free silicon as theimpurity The free silicon may be derived from a silicon substrate and/ora silicon component, etc. The silicon component may be a componentapplied to a semiconductor equipment such as a focus ring. The freesilicon may be included in a content of about 0.01% by weight to about10% by weight in the silicon carbide raw material.

The silicon carbide raw material may further include a metallicimpurity. The metallic impurity may be at least one selected from thegroup consisting of lithium, boron, sodium, aluminum, phosphorus,potassium, calcium, titanium, vanadium, chromium, manganese, iron,nickel, copper, zinc, strontium, zirconium, molybdenum, tin, barium,tungsten, and lead.

The content of the metallic impurity may be about 0.1 ppm to 13 ppm. Thecontent of the metallic impurity may be about 0.3 ppm to 12 ppm. Thecontent of the metallic impurity may be about 0.5 ppm to 8 ppm. Thecontent of the metallic impurity may be about 0.8 ppm to 10 ppm. Thecontent of the metallic impurity may be about 1 ppm to 6 ppm. Thecontent of the metallic impurity may be about 0.1 ppm to 5 ppm. Thecontent of the metallic impurity may be about 0.5 ppm to 3 ppm. Thecontent of the metallic impurity may be about 0.5 ppm to 2 ppm. Thesilicon carbide raw material may further include a metallic impurity.

The silicon carbide raw material may further include a non-metallicimpurity. The non-metallic impurity may be selected from the groupconsisting of fluorine, nitrogen, chlorine, and phosphorus.

The content of the non-metallic impurity may be about 0.01 ppm to 13ppm. The content of the non-metallic impurity may be about 0.03 ppm to12 ppm. The content of the non-metallic impurity may be about 0.05 ppmto 8 ppm. The content of the non-metallic impurity may be about 0.08 ppmto 10 ppm. The content of the non-metallic impurity may be about 0.1 ppmto 6 ppm. The content of the non-metallic impurity may be about 0.1 ppmto 5 ppm. The content of the non-metallic impurity may be about 0.5 ppmto 3 ppm. The content of the non-metallic impurity may be about 0.5 ppmto 2 ppm.

The silicon carbide raw material may have a lump shape. The siliconcarbide raw material may have a plate shape.

The silicon carbide raw material includes about 30% by weight or more ofparticles having diameter of about 1 mm or more. The silicon carbide rawmaterial may include about 50% by weight or more of particles havingdiameter of about 1 mm or more. The silicon carbide raw material mayinclude about 70% by weight or more of particles having diameter ofabout 1 mm or more.

The silicon carbide raw material includes about 30% by weight or more ofparticles having diameter of about 10 mm or more. The silicon carbideraw material may include about 50% by weight or more of particles havingdiameter of about 10 mm or more. The silicon carbide raw material mayinclude about 70% by weight or more of particles having diameter ofabout 10 mm or more.

Here, a sphere having the same volume as the volume of the particle isassumed, and the diameter of the sphere is defined as the particlediameter.

In addition, the silicon carbide raw material may be derived from asubstrate including silicon carbide. The silicon carbide raw materialmay be derived from a wafer entirely including silicon carbide. Thesilicon carbide raw material may be derived from a silicon carbidelayer, deposited on a substrate, such as silicon.

In addition, the silicon carbide raw material may be derived from asilicon carbide monocrystal ingot. The silicon carbide monocrystal ingotmay be discarded due to defects occurring during the manufacturingprocess. Alternatively, the silicon carbide raw material may be derivedfrom a silicon carbide polycrystal.

The silicon carbide raw material may be derived from a silicon carbidesintered body. The silicon carbide sintered body may be formed bysintering a silicon carbide powder. The silicon carbide sintered bodymay be a component included in semiconductor manufacturing equipment.

The silicon carbide raw material may be derived from a graphitecomponent including a silicon carbide layer. The graphite component mayinclude a crucible for forming a silicon carbide ingot, etc.

The silicon carbide raw material may be derived from a component of asemiconductor equipment including a silicon carbide layer. The siliconcarbide layer may be formed by depositing silicon carbide on the surfaceon a silicon component, etc. by a chemical vapor deposition (CVD)process.

The method of manufacturing a silicon carbide powder according to anembodiment may include a step of cutting the silicon carbide rawmaterial.

When the silicon carbide raw material is too large, the silicon carbideraw material may be cut a wire saw or bar cutting by including diamondabrasive grains, etc. The silicon carbide raw material may be cut to alength of 150 mm.

The method of manufacturing a silicon carbide powder according to anembodiment may include a step of crushing a silicon carbide rawmaterial.

The step of crushing a silicon carbide raw material may be a process ofbreaking the silicon carbide raw material into particles having anaverage particle diameter of about 100 mm or less. By the crushingprocess, the silicon carbide raw material may be split into particleshaving an average particle diameter of about 80 mm or less. By thecrushing process, the silicon carbide raw material may be split intoparticles having an average particle diameter of about 60 mm or less. Bythe crushing process, the silicon carbide raw material may be split intoparticles having an average particle diameter of about 50 mm or less. Bythe crushing process, the silicon carbide raw material may be split intoparticles having an average particle diameter of about 0.1 mm to about50 mm. By the crushing process, the silicon carbide raw material may besplit into particles having an average particle diameter of about 1 mmto about 40 mm.

In the crushing process, a jaw crusher, a cone crusher, or a gyratorycrusher may be used.

The jaw crusher includes a pair of compression plates, and the siliconcarbide raw material is inserted between the compression plates. Thesilicon carbide raw material is crushed by the pressure applied throughthe compression plates, and the crushed silicon carbide raw material maybe discharged downward by magnetic gravity.

Each of the compression plates may include at least one of steel,stainless steel, manganese-added steel, chromium-added steel,nickel-added steel, molybdenum-added steel, nitrogen-added steel, andtungsten carbide. A portion of the compression plate in direct contactwith the silicon carbide raw material may be made of at least one ofsteel, stainless steel, manganese-added steel, chromium-added steel,nickel-added steel, molybdenum-added steel, nitrogen-added steel, andtungsten carbide. A portion of the compression plate in direct contactwith the silicon carbide raw material may be coated with the tungstencarbide.

The gyratory crusher includes a crushing head and a crushing bowlaccommodating the crushing head. The crushing head has a truncated coneshape, and the crushing head is mounted on a shaft. An upper end of thecrushing head is fixed to a flexible bearing, and a lower end of thecrushing head is driven eccentrically to draw a circle. The crushingaction is made around the entire cone, and the maximum movement is madeat the bottom. Accordingly, since the crushing of the gyratory crushercontinues to operate, the gyratory crusher has less stress fluctuationand lower power consumption than the jaw crusher.

Like the jaw crusher, the crushing head and the crushing bowl which areparts in direct contact with the silicon carbide raw material mayinclude at least one of steel, stainless steel, manganese-added steel,chromium-added steel, nickel-added steel, molybdenum-added steel,nitrogen-added steel, and tungsten carbide. Portions of the crushinghead and the crushing bowl which are in direct contact with the siliconcarbide raw material may be made of at least one of steel, stainlesssteel, manganese-added steel, chromium-added steel, nickel-added steel,molybdenum-added steel, nitrogen-added steel, and tungsten carbide.Portions of the crushing head and the crushing bowl in direct contactwith the silicon carbide raw material may be coated with the tungstencarbide.

The cone crusher is a device for the silicon carbide raw material byimpact force and compression force. The cone crusher has a similarstructure and crushing motion to the gyratory crusher. However, the conecrusher may have shorter cones. The cone crusher includes anumbrella-shaped cone mantle head mounted on a vertical central axis. Bythe eccentric motion of the cone mantle head, the silicon carbide rawmaterial is bitten into a cone cave bowl, and as it goes down, thesilicon carbide raw material is crushed.

Like the jaw crusher, the cone mantle head and the cone cave bowl whishare parts in direct contact with the silicon carbide raw material mayinclude at least one of steel, stainless steel, manganese-added steel,chromium-added steel, nickel-added steel, molybdenum-added steel,nitrogen-added steel, and tungsten carbide. Portions of the cone mantlehead and the cone cave bowl in direct contact with the silicon carbideraw material may be made of at least one of steel, stainless steel,manganese-added steel, chromium-added steel, nickel-added steel,molybdenum-added steel, nitrogen-added steel, and tungsten carbide.Portion of the cone mantle head and the cone cave bowl in direct contactwith the silicon carbide raw material may be coated with the tungstencarbide.

The method of manufacturing a silicon carbide powder according to anembodiment may include a step of pulverizing a silicon carbide rawmaterial.

The step of pulverizing a silicon carbide raw material may include aprocess of breaking the silicon carbide raw material into particleshaving a diameter of about 30 mm or less. By the pulverization process,the silicon carbide raw material may be split into particles having anaverage particle diameter of about 20 mm or less. By the pulverizationprocess, the silicon carbide raw material may be split into particleshaving an average particle diameter of about 15 mm or less. By thepulverization process, the silicon carbide raw material may be splitinto particles having an average particle diameter of about 10 mm orless. By the pulverization process, the silicon carbide raw material maybe split into particles having an average particle diameter of about 0.1mm to about 10 mm. By the pulverization process, the silicon carbide rawmaterial may be split into particles having an average particle diameterof about 0.1 mm to about 8 mm. By the pulverization process, the siliconcarbide raw material may be split into particles having an averageparticle diameter of about 0.01 mm to about 6 mm.

In the pulverization process, a ball mill, a hammer crusher, a jet mill,or the like may be used.

The ball mill may include a metal cylinder and a ball. The ball and thesilicon carbide raw material are placed in the metal cylinder. When themetal cylinder rotates, the ball and the silicon carbide raw materialcan be rotated by the friction between the ball and the silicon carbideraw material and the centrifugal force within the metal cylinder. Atthis time, the ball and the silicon carbide raw material rise to acertain height in the cylinder, and then fall, and the silicon carbideraw material is pulverized and polished. Depending on the rotationalspeed of the cylinder, the inner diameter of the cylinder, the size ofthe ball, the material of the ball, and the time of the pulverizationprocess, the silicon carbide raw material may be split into particleshaving a small diameter.

The metal cylinder and the ball which are parts in direct contact withthe silicon carbide raw material may include at least one of steel,stainless steel, manganese-added steel, chromium-added steel,nickel-added steel, molybdenum-added steel, nitrogen-added steel, andtungsten carbide. Portion of the metal cylinder and the ball in directcontact with the silicon carbide raw material may be made of at leastone of steel, stainless steel, manganese-added steel, chromium-addedsteel, nickel-added steel, molybdenum-added steel, nitrogen-added steel,and tungsten carbide. Portions of the metal cylinder and the ball indirect contact with the silicon carbide raw material may be coated withthe tungsten carbide.

The hammer crusher includes a chamber and multiple hammers. The hammersare mounted on a rotating body placed within the chamber. The hammersrotate within the chamber, and the hammers impact on the silicon carbideraw material. Accordingly, the silicon carbide raw material may be splitinto particles having a small diameter.

The chamber and the hammers which are parts in direct contact with thesilicon carbide raw material may include at least one of steel,stainless steel, manganese-added steel, chromium-added steel,nickel-added steel, molybdenum-added steel, nitrogen-added steel, andtungsten carbide. Portions of the chamber and the hammers in directcontact with the silicon carbide raw material may be made of at leastone of steel, stainless steel, manganese-added steel, chromium-addedsteel, nickel-added steel, molybdenum-added steel, nitrogen-added steel,and tungsten carbide. Portions of the chamber and the hammers in directcontact with the silicon carbide raw material may be coated with thetungsten carbide.

The jet mill pulverizes the silicon carbide raw material by mutuallycolliding the silicon carbide raw material with the energy of injectionfrom the nozzle by the pressure of a fluid. The silicon carbide rawmaterial is pulverized in the chamber until the particle size thereofreaches a desired size. In addition, the particles subjected to thepulverization process are collected through a classification chamberfrom the chamber. Since the jet mill pulverizes the silicon carbide rawmaterial by mutual collision of the silicon carbide raw material by thepressure of fluid, the contamination of the silicon carbide raw materialby direct contact with other devices may be minimized.

The chamber which is a part in direct contact with the silicon carbideraw material may include at least one of steel, stainless steel,manganese-added steel, chromium-added steel, nickel-added steel,molybdenum-added steel, nitrogen-added steel, and tungsten carbide. Aportion of the chamber which is in direct contact with the siliconcarbide raw material may be made of at least one of steel, stainlesssteel, manganese-added steel, chromium-added steel, nickel-added steel,molybdenum-added steel, nitrogen-added steel, and tungsten carbide. Aportion of the chamber which is in direct contact with the siliconcarbide raw material may be coated with the tungsten carbide.

The method of manufacturing a silicon carbide powder according to anembodiment may further include a step of removing iron by magneticforce.

The step of removing an iron component may be a step of removing ironadsorbed to the silicon carbide raw material in the crushing andpulverizing steps.

In the step of removing an iron component, a rotary metal detector maybe used to remove the iron.

A rotation speed of the rotary metal detector may be about 100 rpm toabout 800 rpm, and an output of an electromagnet included in the rotarymetal detector may be about 0.5 kW to about 3 kW. In addition, arotation speed of the rotary metal detector may be about 800 rpm toabout 1700 rpm, and an output of an electromagnet included in the rotarymetal detector may be about 3 kW to about 5 kW.

The content of iron contained in the silicon carbide raw material fromwhich iron has been removed may be about 1 ppm or less. The content ofiron contained in the silicon carbide raw material from which iron hasbeen removed about 0.5 ppm or less. The content of iron contained in thesilicon carbide raw material from which iron has been removed about 0.3ppm or less. The content of iron contained in the silicon carbide rawmaterial from which iron has been removed about 0.1 ppm or less.

The method of manufacturing a silicon carbide powder according to anembodiment includes a step of removing the carbon-based material.

The step of removing the carbon-based material may include a step ofphysically removing the carbon-based material.

The step of physically removing the carbon-based material may include asteel cut wire shot process. A wire used for the steel cut wire shot maybe made of carbon steel, stainless steel, aluminum, zinc, nickel,copper, or an alloy thereof, but is not limited thereto. In addition,the diameter of the wire may be about 0.2 mm to about 0.8 mm. Thediameter of the wire may be about 0.4 mm to about 0.6 mm.

A rotation speed of the wire may be about 1000 rpm to about 5000 rpm.

In addition, the step of physically removing the carbon-based materialmay include a blasting process such as sand blasting or short blasting.The blasting process may be a process of spraying fine particles on thecarbon-based material such as graphite to remove the carbon-basedmaterial. That is, since the carbon-based material has a lower hardnessthan the silicon carbide, it can be removed easily by fine particlessprayed with an appropriate pressure.

In addition, the step of physically removing the carbon-based materialmay include a separation process using density difference, such ascentrifugation. The crushed and/or pulverized silicon carbide rawmaterial may be separated by a density difference between thecarbon-based material and the silicon carbide. That is, since thedensity of silicon carbide is larger than the density of graphite, thecarbon-based material may be easily removed by density gradientcentrifugation, etc.

After the step of physically removing the carbon-based material, thecontent of the carbon-based material included in the raw material may beabout 5% by weight or less. After the step of removing the carbon-basedmaterial, the content of the carbon-based material included in the rawmaterial may be about 3% by weight or less. After the step of removingthe carbon-based material, the content of the carbon-based materialincluded in the raw material may be about 1% by weight or less.

In addition, the step of removing the carbon-based material includes astep of chemically removing the carbon-based material.

The step of chemically removing the carbon-based material includes astep of oxidizing the carbon-based material.

After the carbon-based material contained in the raw material issufficiently removed, the raw material is heat-treated in an oxygen oratmospheric atmosphere. At this time, the oxidative heat treatmenttemperature may be about 1000° C. to about 1200° C. The heat treatmenttime may be about 12 hours to about 48 hours.

Since the raw material is heat-treated in the above time and temperatureranges, the carbon-based material contained in the raw material may beeffectively removed. In addition, since the raw material is heat-treatedin the above time and temperature ranges, the generation of by-productssuch as silicon oxide in the raw material may be minimized.

The method of manufacturing a silicon carbide powder according to anembodiment includes a step of classifying the silicon carbide rawmaterial. In the classifying step, the silicon carbide raw materialgranulated through the crushing process and the pulverizing process maybe classified.

The granulated silicon carbide raw material may be classified by a meshof a desired size.

The classifying step may be performed using a twist screen that is avibrating classifying device.

The twist screen may include a silicon material-made tapping ball havinga diameter of 10 mm to 80 mm, 15 mm to 70 mm, or 20 mm to 60 mm. Usingthe twist screen, the classifying step may be performed for about 10minutes to about 100 minutes under a vibration condition of about 1000times/minute to about 3000 times/minute.

The granulated silicon carbide raw material may be fed into the twistscreen at a constant speed.

The particle diameter (D50) of the granulated silicon carbide rawmaterial may be about 10 μm to about 10000 μm. The particle diameter(D50) of the granulated silicon carbide raw material may be about 100 μmto about 6000 μm. The particle diameter (D50) of the granulated siliconcarbide raw material may be about 60 μm to about 5000 μm. The particlediameter (D50) of the granulated silicon carbide raw material may beabout 100 μm to about 4000 μm. The particle diameter (D50) of thegranulated silicon carbide raw material may be about 150 μm to about 400μm. The particle diameter (D50) of the granulated silicon carbide rawmaterial may be about 300 μm to about 800 μm. The particle diameter(D50) of the granulated silicon carbide raw material may be about 500 μmto about 1000 μm. The particle diameter (D50) of the granulated siliconcarbide raw material may be about 700 μm to about 2000 μm. The particlediameter (D50) of the granulated silicon carbide raw material may beabout 1000 μm to about 3000 μm.

The method of manufacturing a silicon carbide powder according to anembodiment may include a step of wet etching the silicon carbide rawmaterial.

The wet etching step is carried out by an etchant. The silicon carbideraw material that has undergone the crushing and pulverizing processesmay be subjected to the wet etching step.

The etchant may include water and acid. The acid may be at least oneselected from the group consisting of hydrofluoric acid, nitric acid,hydrochloric acid, and sulfuric acid.

The etchant may include water, hydrofluoric acid, and nitric acid.

The hydrofluoric acid may be included in a content of about 5 parts byweight to about 40 parts by weight based on 100 parts by weight of thewater in the etchant. The hydrofluoric acid may be included in a contentof about 10 parts by weight to about 35 parts by weight based on 100parts by weight of the water in the etchant. The hydrofluoric acid maybe included in a content of about 12.5 parts by weight to about 30 partsby weight based on 100 parts by weight of the water in the etchant.

The nitric acid may be included in a content of about 3 parts by weightto about 30 parts by weight based on 100 parts by weight of the water inthe etchant. The nitric acid may be included in a content of about 4parts by weight to about 25 parts by weight based on 100 parts by weightof the water in the etchant. The nitric acid may be included in acontent of about 5 parts by weight to about 20 parts by weight based on100 parts by weight of the water in the etchant.

The etchant may be filled in an etch vessel. Here, the etchant may befilled in an amount of about 10 vol % to about 20 vol % based on thetotal volume of the etch vessel in the etch vessel. The etchant may befilled in an amount of about 12 vol % to about 18 vol % based on thetotal volume of the etch vessel in the etch vessel. In addition, thesilicon carbide raw material may be filled in an amount of about 10 vol% to about 30 vol % based on the total volume of the etch vessel in theetch vessel. The silicon carbide raw material may be filled in an amountof about 15 vol % to about 25 vol % based on the total volume of theetch vessel in the etch vessel. When the silicon carbide raw material isfilled in the etch vessel, the volume of the silicon carbide rawmaterial may be measured as an apparent volume.

The silicon carbide raw material may be wet-etched by the etchant. Thatis, the surface of the silicon carbide raw material may be etched by theetchant, and impurities remaining on the surface of the silicon carbideraw material may be removed by the etchant.

The wet etching step may be carried out according to the followingprocesses.

First, the etch vessel and the silicon carbide raw material may bedried. The etch vessel and the silicon carbide raw material may be driedwith hot air at about 50° C. to about 150° C. for about 10 minutes toabout 1 hour.

Next, the silicon carbide raw material is placed in the etch vessel.

Next, the etchant is fed into the etch vessel in which the siliconcarbide raw material has been placed.

A process of feeding the etchant may be as follows.

First, deionized water is fed into the etch vessel in which the siliconcarbide raw material has been placed.

Next, hydrofluoric acid is fed into the etch vessel into which thedeionized water has been fed.

Next, nitric acid is fed into the etch vessel into which thehydrofluoric acid has been fed.

Next, the etch vessel into which the etchant has been fed is sealed by alid, the silicon carbide raw material and etchant contained in the etchvessel are stirred at a speed of about 50 rpm to about 500 rpm. Thestirring time may be about 30 minutes to about 2 hours.

Next, the etchant is drained, and the silicon carbide raw materialsubjected to the wet etching process is precipitated several times indeionized water and neutralized. At this time, after precipitation, theneutralization process of the silicon carbide raw material that hasundergone the wet etching process may be completed based on the contentand/or pH of hydrofluoric acid contained in the drained wastewater. Whenthe pH of the wastewater is 6.8 to 7.2, the neutralization process maybe finished.

The method of manufacturing a silicon carbide powder according to anembodiment may include a step of dry etching the silicon carbide rawmaterial.

The dry etching process may be performed by spraying an etching gas ontothe silicon carbide raw material.

The etching gas may include a chlorine gas. The etching gas may furtherinclude an inert gas such as argon as a carrier gas.

The dry etching process may be carried out as follows.

First, a dry etching furnace is prepared. The dry etching furnace may bemade of graphite and may be heated to a temperature of about 2000° C. ormore. The dry etching furnace is sealed against the outside, and theinside of the dry etching furnace may be depressurized up to about 5torr or less.

The silicon carbide raw material is placed in the dry etching furnace.

Next, the dry etching furnace is heated up to a temperature of about1800° C. to about 2200° C.

Next, the inside of the dry etching furnace is depressurized to apressure of about 1 torr to about 30 torr. The inside of the dry etchingfurnace is depressurized to a pressure of about 1 torr to about 10 torr.The inside of the dry etching furnace is depressurized to a pressure ofabout 1 torr to about 8 torr.

Next, the etching gas is fed into the dry etching furnace. The etchinggas may be convected in the dry etching furnace by a temperaturedifference between the lower portion and the upper portion of the dryetching furnace. That is, the temperature of the lower portion of thedry etching furnace is about 50° C. to about 100° C. higher than thetemperature of the upper portion of the dry etching furnace, so that theetching gas at the lower portion of the dry etching furnace moves to theupper portion of the dry etching furnace, thereby dry etching thesurface of the silicon carbide raw material. The residence time of theetching gas in the dry etching furnace may be about 24 hours to about 96hours.

Next, the etching gas may be removed by a wet scrubber, and the pressureof the inside of the dry etching furnace may be increased to about 600torr to about 780 torr.

The dry etching process may additionally include a heat treatmentprocess and an oxide film removal process.

The dry-etched silicon carbide particles may be heat-treated at about700° C. to about 1300° C. in an atmosphere containing oxygen in the dryetching furnace. The dry-etched silicon carbide particles may beheat-treated at about 800° C. to about 1200° C. in an atmospherecontaining oxygen in the dry etching furnace. The dry-etched siliconcarbide particles may be heat-treated at about 900° C. to about 1100° C.in an atmosphere containing oxygen in the dry etching furnace. The heattreatment time may be about 10 minutes to about 2 hours. The heattreatment time may be about 20 minutes to about 1 hour.

By the heat treatment, chlorine remaining on the surface of thedry-etched silicon carbide particles may be easily removed.

The oxide film removal process may include a wet etching process.

The heat-treated silicon carbide raw material is fed into an etchvessel, and deionized water and hydrofluoric acid are additionally fedinto the etch vessel.

Next, the silicon carbide raw material and etchant in the etch vesselmay be stirred, and an oxide film on the surface of the silicon carbideraw material may be removed.

The silicon carbide raw material from which the oxide film has beenremoved is neutralized by deionized water.

The method of manufacturing a silicon carbide powder according to anembodiment may include a step of cleaning the silicon carbide rawmaterial.

The cleaning process may be carried out using a cleaning solutionincluding at least one selected from the group consisting ofhydrofluoric acid, distilled water, and ultrapure water.

The cleaning process may include a first cleaning step, a firsthydrofluoric acid treatment step, a second cleaning step, a secondhydrofluoric acid treatment step, and a third cleaning step.

The first cleaning step may be performed for 1 minute to 300 minutesusing distilled water, ultrapure water, or pure water. For example, thefirst cleaning step may be performed for about 1 minute to about 250minutes, about 1 minute to about 200 minutes, about 3 minutes to about150 minutes, about 10 minutes to about 100 minutes, about 15 minutes toabout 80 minutes, about 20 minutes to about 60 minutes, or about 20minutes to about 40 minutes.

Next, the first hydrofluoric acid treatment step is a step of cleaningthe silicon carbide raw material using a cleaning solution includinghydrofluoric acid. The silicon carbide raw material may be stirred forabout 1 minute to about 300 minutes, about 1 minute to about 250minutes, about 1 minute to about 200 minutes, about 3 minutes to about150 minutes, about 10 minutes to about 100 minutes, about 15 minutes toabout 80 minutes, about 20 minutes to about 60 minutes or about 20minutes to about 40 minutes in the cleaning solution. Next, the siliconcarbide raw material may be precipitated in the cleaning solution. Thesilicon carbide raw material may be precipitated for about 1 minute toabout 300 minutes, about 1 minute to about 250 minutes, about 1 minuteto about 200 minutes, about 3 minutes to about 150 minutes, about 10minutes to about 100 minutes, about 15 minutes to about 80 minutes,about 20 minutes to about 60 minutes, or about 20 minutes to about 40minutes in the cleaning solution.

The second cleaning step may be performed for 1 minute to 300 minutesusing distilled water, ultrapure water, or pure water. For example, thesecond cleaning step may be performed for about 1 minute to about 250minutes, about 1 minute to about 200 minutes, about 3 minutes to about150 minutes, about 10 minutes to about 100 minutes, about 15 minutes toabout 80 minutes, about 20 minutes to about 60 minutes, or about 20minutes to about 40 minutes.

Next, the second hydrofluoric acid treatment step is a step of cleaningthe silicon carbide raw material using a cleaning solution includinghydrofluoric acid. The silicon carbide raw material may be stirred forabout 1 minute to about 300 minutes, about 1 minute to about 250minutes, about 1 minute to about 200 minutes, about 3 minutes to about150 minutes, about 10 minutes to about 100 minutes, about 15 minutes toabout 80 minutes, about 20 minutes to about 60 minutes, or about 20minutes to about 40 minutes in the cleaning solution. Next, the siliconcarbide raw material may be precipitated in the cleaning solution. Thesilicon carbide raw material may be precipitated for about 1 minute toabout 300 minutes, about 1 minute to about 250 minutes, about 1 minuteto about 200 minutes, about 3 minutes to about 150 minutes, about 10minutes to about 100 minutes, about 15 minutes to about 80 minutes,about 20 minutes to about 60 minutes, or about 20 minutes to about 40minutes in the cleaning solution.

The third cleaning step may be performed for 1 minute to 300 minutesusing distilled water, ultrapure water, or pure water. For example, thethird cleaning step may be performed for about 1 minute to about 250minutes, about 1 minute to about 200 minutes, about 3 minutes to about150 minutes, about 10 minutes to about 100 minutes, about 15 minutes toabout 80 minutes, about 20 minutes to about 60 minutes, or about 20minutes to about 40 minutes.

By the graphite removal process, the iron component removal process, thewet etching process, the dry etching process, and the cleaning process,the silicon carbide powder according to an embodiment may have a veryhigh purity.

Referring to FIG. 1 , a silicon carbide powder according to oneembodiment may be manufactured by the following process.

First, the silicon carbide raw material is crushed in the crushingprocess (S10).

Next, by the carbon-based material removal process, a carbon-basedmaterial such as graphite included in the silicon carbide raw materialis removed (S20).

Next, the silicon carbide raw material from which a carbon-basedmaterial has been removed is pulverized by the pulverization process(S30).

Next, the pulverized silicon carbide raw material is etched by a wetetching process (S40). Accordingly, impurities adhering to the surfaceof the pulverized silicon carbide may be efficiently removed. Inparticular, the carbon-based material remaining in the pulverizedsilicon carbide raw material may float in the etchant and may react withhydrofluoric acid, etc. included in the etchant. Accordingly, in the wetetching process, not only metallic impurities but also the carbon-basedmaterial may be efficiently removed.

Next, the wet etched silicon carbide raw material is etched by a dryetching process (S50).

Next, the dry-etched silicon carbide raw material is subjected to acleaning process (S60).

Next, the cleaned silicon carbide raw material may be classified intoparticles having a desired particle size (S70).

Referring to FIG. 2 , a silicon carbide powder according to oneembodiment may be manufactured by the following process.

In this embodiment, a process substantially the same as the process ofFIG. 1 is carried out, but before the crushing process, a carbon-basedmaterial removal process may be carried out (S1).

When the silicon carbide raw material contains a large amount of carbonas an impurity, the carbon-based material removal process may bepreceded. For example, when the silicon carbide raw material includes agraphite component in a high ratio as in a graphite component coatedwith silicon carbide, the carbon-based material removal process may beperformed first.

Since the carbon-based material is first removed (S1) and then thecrushing process (S10) is performed, the carbon-based material includedin the silicon carbide raw material may be efficiently removed.

Therefore, the method of manufacturing a silicon carbide powderaccording to the embodiment may provide a silicon carbide powder of highpurity by using a silicon carbide raw material including a carbon-basedmaterial in a high content.

Referring to FIG. 3 , a silicon carbide powder according to oneembodiment may be manufactured by the following process.

In this embodiment, a process substantially the same as the process ofFIG. 1 is carried out, but the carbon-based material removal process maybe omitted.

When the silicon carbide raw material does not include the carbon-basedmaterial such as graphite or includes the same in a very low content,the carbon-based material removal process may be omitted. For example,the silicon carbide raw material may include silicon carbide in anamount of about 95% by weight or more as in a monocrystal siliconcarbide ingot, polycrystal silicon carbide, or a silicon carbidesintered body. In this case, in the wet etching process, etc., a smallamount of carbon-based material is removed so that a silicon carbidepowder with high purity may be obtained without a separate additionalprocess.

Referring to FIGS. 4 to 6 , the silicon carbide powder according to oneembodiment may be manufactured by the following process.

In this embodiment, a process substantially the same as the process ofFIG. 1, 2 , or 3 is carried out, but the classification process (S31)may be performed immediately after the pulverization process (S30). Thatis, the pulverized silicon carbide raw material may be classified intoparticles having a desired particle size by the classification processperformed immediately after the pulverization process. The classifiedsilicon carbide raw material may be subjected to the wet etchingprocess, the dry etching process, and the cleaning process.

In this embodiment, since the silicon carbide raw material is subjectedto the wet etching process and the dry etching process after beingclassified into particles having a uniform particle diameter, the entiresurface of the silicon carbide raw material may be uniformly etched. Inparticular, since the silicon carbide raw material is classified intoparticles having a uniform particle diameter, the space between theparticles of the silicon carbide raw material may be uniformly formed.Accordingly, the etching gas may uniformly permeate into the spacebetween the silicon carbide raw material particles, and the dry etchingprocess may uniformly etch the silicon carbide raw materials as a whole.

Accordingly, the method of manufacturing a silicon carbide powderaccording to the embodiment may uniformly control the content of carbon,silicon, and oxygen included in the surface of the silicon carbide rawmaterial as a whole.

The purity of the silicon carbide powder according to an embodiment maybe about 99.99% or more. The purity of the silicon carbide powderaccording to an embodiment may be about 99.999% or more. The purity ofthe silicon carbide powder according to an embodiment may be about99.9999% or more. The purity of the silicon carbide powder according toan embodiment may be about 99.999999% or more. The purity of the siliconcarbide powder according to an embodiment may be about 99.9999999% ormore. The purity of the silicon carbide powder according to anembodiment may be about 99.9999999% or more. The purity of the siliconcarbide powder according to an embodiment may be about 99.99999999% ormore.

The silicon carbide powder according to an embodiment may include atleast one impurity selected from the group consisting of lithium,sodium, magnesium, aluminum, potassium, calcium, titanium, vanadium,chromium, manganese, iron, cobalt, nickel, copper, zinc, and molybdenumin an amount of about 1 ppm or less, about 0.8 ppm or less, about 0.7ppm or less, about 0.1 to about 0.7 ppm or about 0.1 to about 0.6 ppm.

In addition, the particle diameter (D50) of the silicon carbide powderaccording to an embodiment may be about 10 μm to about 10000 μm. Theparticle diameter (D50) of the silicon carbide powder according to anembodiment may be about 100 μm to about 6000 μm. The particle diameter(D50) of the silicon carbide powder according to an embodiment may beabout 60 μm to about 5000 μm. The particle diameter (D50) of the siliconcarbide powder according to an embodiment may be about 100 μm to about4000 μm. The particle diameter (D50) of the silicon carbide powderaccording to an embodiment may be about 150 μm to about 400 μm. Theparticle diameter (D50) of the silicon carbide powder according to anembodiment may be about 300 μm to about 800 μm. The particle diameter(D50) of the silicon carbide powder according to an embodiment may beabout 500 μm to about 1000 μm. The particle diameter (D50) of thesilicon carbide powder according to an embodiment may be about 700 μm toabout 2000 μm. The particle diameter (D50) of the silicon carbide powderaccording to an embodiment may be about 1000 μm to about 3000 μm.

The silicon carbide powder according to an embodiment may includeelemental oxygen on the surface thereof in an appropriate content.

The content of oxygen included in the surface of the silicon carbidepowder according to an embodiment may be about 3 atom % to about 23 atom%. The content of oxygen included in the surface of the silicon carbidepowder according to an embodiment may be about 4 atom % to about 20 atom%. The content of oxygen included in the surface of the silicon carbidepowder according to an embodiment may be about 4 atom % to about 18 atom%. The content of oxygen included in the surface of the silicon carbidepowder according to an embodiment may be about 4 atom % to about 15 atom%. The content of oxygen included in the surface of the silicon carbidepowder according to an embodiment may be about 4 atom % to about 13 atom%. The content of oxygen included in the surface of the silicon carbidepowder according to an embodiment may be about 4 atom % to about 11 atom%. The content of oxygen included in the surface of the silicon carbidepowder according to an embodiment may be about 5 atom % to about 10 atom%.

The content of oxygen included in the surface of the silicon carbidepowder may be measured by X-ray photoelectron spectroscopy.

In the X-ray photoelectron spectroscopy, the X-ray source may bemonochromated Al X-Ray sources, and the Al Ka line may be about 1300 eVto about 1600 eV.

In addition, in the X-ray photoelectron spectroscopy, the X-ray powermay have a voltage of about 10 kV to about 14 kV and a current of about8 mA to about 12 mA.

In addition, in the X-ray photoelectron spectroscopy, the diameter of asampling area may be about 300 μm to about 500 μm. In the X-rayphotoelectron spectroscopy, a pass energy in a narrow scan may be about30 eV to about 50 eV. In the X-ray photoelectron spectroscopy, a stepsize in the narrow scan may be about 0.03 eV to about 0.07 eV. Inaddition, in the X-ray photoelectron spectroscopy, a pressure may beabout 10⁻⁹ mbar to 5×10⁻⁹ mbar. In addition, in the X-ray photoelectronspectroscopy, an etching condition may be argon ion etching of about 1keV to about 3 keV and a raster size of about 1 mm×1 mm to about 3 mm×3mm.

In the silicon carbide powder according to an embodiment, an elementratio in the surface may be measured by the X-ray photoelectronspectroscopy. For example, by the X-ray photoelectron spectroscopy, asurvey spectrum or a multiplex spectrum may be obtained. A peak area ofeach element is derived from the survey spectrum or the multiplexspectrum through integration. A value obtained by dividing the peak areaof an element by the sensitivity of each element may be a relativeamount of each element. Accordingly, the ratio of each element may beobtained.

In the silicon carbide powder according to an embodiment, O1s/C1s of thesurface measured by the X-ray photoelectron spectroscopy may be about0.29 or less. In the silicon carbide powder according to an embodiment,O1s/C1s of the surface measured by the X-ray photoelectron spectroscopymay be about 0.28 or less. In the silicon carbide powder according to anembodiment, O1s/C1s of the surface measured by the X-ray photoelectronspectroscopy may be about 0.27 or less. In the silicon carbide powderaccording to an embodiment, O1s/C1s of the surface measured by the X-rayphotoelectron spectroscopy may be about 0.26 or less. In the siliconcarbide powder according to an embodiment, O1s/C1s of the surfacemeasured by the X-ray photoelectron spectroscopy may be about 0.25 orless. In the silicon carbide powder according to an embodiment, O1s/C1sof the surface measured by the X-ray photoelectron spectroscopy may beabout 0.24 or less. In the silicon carbide powder according to anembodiment, a minimum value of O1s/C1s of the surface measured by theX-ray photoelectron spectroscopy may be about 0.05.

In addition, in the silicon carbide powder according to an embodiment,O1s/C1s of the surface measured by the X-ray photoelectron spectroscopymay be about 0.05 to about 0.29. In the silicon carbide powder accordingto an embodiment, O1s/C1s of the surface measured by the X-rayphotoelectron spectroscopy may be about 0.05 to about 0.28. In thesilicon carbide powder according to an embodiment, O1s/C1s of thesurface measured by the X-ray photoelectron spectroscopy may be about0.07 to about 0.27. In the silicon carbide powder according to anembodiment, O1s/C1s of the surface measured by the X-ray photoelectronspectroscopy may be about 0.1 to about 0.26. In the silicon carbidepowder according to an embodiment, O1s/C1s of the surface measured bythe X-ray photoelectron spectroscopy may be about 0.13 to about 0.25. Inthe silicon carbide powder according to an embodiment, O1s/C1s of thesurface measured by the X-ray photoelectron spectroscopy may be about0.15 to about 0.24.

In the silicon carbide powder according to an embodiment, O1s/Si2p ofthe surface measured by the X-ray photoelectron spectroscopy may beabout 0.39 or less. In the silicon carbide powder according to anembodiment, O1s/Si2p of the surface measured by the X-ray photoelectronspectroscopy may be about 0.38 or less. In the silicon carbide powderaccording to an embodiment, O1s/Si2p of the surface measured by theX-ray photoelectron spectroscopy may be about 0.37 or less. In thesilicon carbide powder according to an embodiment, O1s/Si2p of thesurface measured by the X-ray photoelectron spectroscopy may be about0.36 or less. In the silicon carbide powder according to an embodiment,O1s/Si2p of the surface measured by the X-ray photoelectron spectroscopymay be about 0.32 or less. A minimum value of O1s/Si2p of the surfacemeasured by the X-ray photoelectron spectroscopy may be about 0.05.

In addition, in the silicon carbide powder according to an embodiment,O1s/Si2p of the surface measured by the X-ray photoelectron spectroscopymay be about 0.05 to about 0.39. In the silicon carbide powder accordingto an embodiment, O1s/Si2p of the surface measured by the X-rayphotoelectron spectroscopy may be about 0.05 to about 0.38. In thesilicon carbide powder according to an embodiment, O1s/Si2p of thesurface measured by the X-ray photoelectron spectroscopy may be about0.1 to about 0.37. In the silicon carbide powder according to anembodiment, O1s/Si2p of the surface measured by the X-ray photoelectronspectroscopy may be about 0.1 to about 0.36. In the silicon carbidepowder according to an embodiment, O1s/Si2p of the surface measured bythe X-ray photoelectron spectroscopy may be about 0.15 to about 0.32.

In the silicon carbide powder according to an embodiment, O1s/Si2p ofthe surface measured by the X-ray photoelectron spectroscopy may beabout 0.4 or less. In the silicon carbide powder according to anembodiment, O1s/Si2p of the surface measured by the X-ray photoelectronspectroscopy may be about 0.37 or less. In the silicon carbide powderaccording to an embodiment, O1s/Si2p of the surface measured by theX-ray photoelectron spectroscopy may be about 0.37 or less. In thesilicon carbide powder according to an embodiment, O1s/Si2p of thesurface measured by the X-ray photoelectron spectroscopy may be about0.35 or less. In the silicon carbide powder according to an embodiment,O1s/Si2p of the surface measured by the X-ray photoelectron spectroscopymay be about 0.33 or less. In the silicon carbide powder according to anembodiment, a minimum value of O1s/Si2p of the surface measured by theX-ray photoelectron spectroscopy may be about 0.05.

In the silicon carbide powder according to an embodiment, N1s/C1s of thesurface measured by the X-ray photoelectron spectroscopy may be about0.02 or less. In the silicon carbide powder according to an embodiment,N1s/C1s of the surface measured by the X-ray photoelectron spectroscopymay be about 0.01 or less. In the silicon carbide powder according to anembodiment, N1s/C1s of the surface measured by the X-ray photoelectronspectroscopy may be about 0.008 or less. In the silicon carbide powderaccording to an embodiment, N1s/C1s of the surface measured by the X-rayphotoelectron spectroscopy may be about 0.007 or less. In the siliconcarbide powder according to an embodiment, N1s/C1s of the surfacemeasured by the X-ray photoelectron spectroscopy may be about 0.006 orless. In the silicon carbide powder according to an embodiment, aminimum value of N1s/C1s of the surface measured by the X-rayphotoelectron spectroscopy may be about 0.000001.

In the silicon carbide powder according to an embodiment, Zn2p/C1s ofthe surface measured by the X-ray photoelectron spectroscopy may beabout 0.03 or less. In the silicon carbide powder according to anembodiment, Zn2p/C1s of the surface measured by the X-ray photoelectronspectroscopy may be about 0.023 or less. In the silicon carbide powderaccording to an embodiment, Zn2p/C1s of the surface measured by theX-ray photoelectron spectroscopy may be about 0.01 or less. In thesilicon carbide powder according to an embodiment, Zn2p/C1s of thesurface measured by the X-ray photoelectron spectroscopy may be about0.009 or less. In the silicon carbide powder according to an embodiment,Zn2p/C1s of the surface measured by the X-ray photoelectron spectroscopymay be about 0.006 or less. In the silicon carbide powder according toan embodiment, a minimum value of Zn2p/C1s of the surface measured bythe X-ray photoelectron spectroscopy may be about 0.000001.

In the silicon carbide powder according to an embodiment, Mg1s/C1s ofthe surface measured by the X-ray photoelectron spectroscopy may beabout 0.01 or less. In the silicon carbide powder according to anembodiment, Mg1s/C1s of the surface measured by the X-ray photoelectronspectroscopy may be about 0.009 or less. In the silicon carbide powderaccording to an embodiment, Mg1s/C1s of the surface measured by theX-ray photoelectron spectroscopy may be about 0.008 or less. In thesilicon carbide powder according to an embodiment, Mg1s/C1s of thesurface measured by the X-ray photoelectron spectroscopy may be about0.005 or less. In the silicon carbide powder according to an embodiment,Mg1s/C1s of the surface measured by the X-ray photoelectron spectroscopymay be about 0.004 or less. In the silicon carbide powder according toan embodiment, a minimum value of Mg1s/C1s of the surface measured bythe X-ray photoelectron spectroscopy may be about 0.000001.

In the silicon carbide powder according to an embodiment, Na1s/C1s ofthe surface measured by the X-ray photoelectron spectroscopy may beabout 0.01 or less. In the silicon carbide powder according to anembodiment, Na1s/C1s of the surface measured by the X-ray photoelectronspectroscopy may be about 0.009 or less. In the silicon carbide powderaccording to an embodiment, Na1s/C1s of the surface measured by theX-ray photoelectron spectroscopy may be about 0.008 or less. In thesilicon carbide powder according to an embodiment, Na1s/C1s of thesurface measured by the X-ray photoelectron spectroscopy may be about0.007 or less. In the silicon carbide powder according to an embodiment,Na1s/C1s of the surface measured by the X-ray photoelectron spectroscopymay be about 0.006 or less. In the silicon carbide powder according toan embodiment, a minimum value of Na1s/C1s of the surface measured bythe X-ray photoelectron spectroscopy may be about 0.000001.

In the silicon carbide powder according to an embodiment, Fe2p3/C1s ofthe surface measured by the X-ray photoelectron spectroscopy may beabout 0.01 or less. In the silicon carbide powder according to anembodiment, Fe2p3/C1s of the surface measured by the X-ray photoelectronspectroscopy may be about 0.009 or less. In the silicon carbide powderaccording to an embodiment, Fe2p3/C1s of the surface measured by theX-ray photoelectron spectroscopy may be about 0.008 or less. In thesilicon carbide powder according to an embodiment, Fe2p3/C1s of thesurface measured by the X-ray photoelectron spectroscopy may be about0.007 or less. In the silicon carbide powder according to an embodiment,Fe2p3/C1s of the surface measured by the X-ray photoelectronspectroscopy may be about 0.006 or less. In the silicon carbide powderaccording to an embodiment, a minimum value of Fe2p3/C1s of the surfacemeasured by the X-ray photoelectron spectroscopy may be about 0.000001or less.

In the silicon carbide powder according to an embodiment, F1s/C1s of thesurface measured by the X-ray photoelectron spectroscopy may be about0.01 or less. In the silicon carbide powder according to an embodiment,F1s/C1s of the surface measured by the X-ray photoelectron spectroscopymay be about 0.009 or less. In the silicon carbide powder according toan embodiment, F1s/C1s of the surface measured by the X-rayphotoelectron spectroscopy may be about 0.008 or less. In the siliconcarbide powder according to an embodiment, F1s/C1s of the surfacemeasured by the X-ray photoelectron spectroscopy may be about 0.007 orless. In the silicon carbide powder according to an embodiment, F1s/C1sof the surface measured by the X-ray photoelectron spectroscopy may beabout 0.006 or less. In the silicon carbide powder according to anembodiment, a minimum value of F1s/C1s of the surface measured by theX-ray photoelectron spectroscopy may be about 0.000001.

In addition, at a predetermined depth in the silicon carbide powderaccording to an embodiment, an oxygen concentration in a region wherethe oxygen concentration is constant may be about 7 atom % or less. Thepredetermined depth may be a depth in which an oxygen concentrationchange according to an etching time is about 2 atom %/100 s or less. Inthe predetermined depth, the etching time may be about 100 seconds toabout 800 seconds. In the predetermined depth, the etching time may beabout 200 seconds to about 600 seconds. When the etching time is about200 seconds to about 600 seconds, the predetermined depth may be aregion in which an oxygen concentration change according to the etchingtime is about 2 atom %/100 s or less.

In the silicon carbide powder according to an embodiment, at thepredetermined depth, an oxygen concentration in a region where theoxygen concentration is constant may be about 6 atom % or less. In thesilicon carbide powder according to an embodiment, at the predetermineddepth, an oxygen concentration in a region where the oxygenconcentration is constant may be about 5 atom % or less. In the siliconcarbide powder according to an embodiment, at the predetermined depth,an oxygen concentration in a region where the oxygen concentration isconstant may be about 4.5 atom % or less. In the silicon carbide powderaccording to an embodiment, at the predetermined depth, an oxygenconcentration in a region where the oxygen concentration is constant maybe about 4 atom % or less. In the silicon carbide powder according to anembodiment, at the predetermined depth, an oxygen concentration in aregion where the oxygen concentration is constant may be about 3.5 atom% or less. In the silicon carbide powder according to an embodiment, atthe predetermined depth, an oxygen concentration in a region where theoxygen concentration is constant may be about 3.16 atom % or less. Inthe silicon carbide powder according to an embodiment, at thepredetermined depth, a minimum value of an oxygen concentration in aregion where the oxygen concentration is constant may be about 0.5 atom%.

In the silicon carbide powder according to an embodiment, at thepredetermined depth, an oxygen concentration in a region where theoxygen concentration is constant may be about 0.5 atom % to about 4 atom%. In the silicon carbide powder according to an embodiment, at thepredetermined depth, an oxygen concentration in a region where theoxygen concentration is constant may be about 0.5 atom % to about 4.5atom %. In the silicon carbide powder according to an embodiment, at thepredetermined depth, an oxygen concentration in a region where theoxygen concentration is constant may be about 0.5 atom % to about 4.8atom %. In the silicon carbide powder according to an embodiment, at thepredetermined depth, an oxygen concentration in a region where theoxygen concentration is constant may be about 0.5 atom % to about 5 atom%.

The O1s/C1s, O1s/Si2s, O1s/Si2p, N1s/C1s, Zn2p/C1s, Mg1s/C1s, Na1s/C1s,Fe2p3/C1s and F1s/C1s may be derived by dividing the area of each of O1speak, C1s peak, Si2s peak, Si2p peak, N1s peak, Zn2p peak, Mg1s peak,Na1s peak, Fe2p3 peak, and F1s peak by the sensitivity of each elementin the graph of binding energy and counts per second (count/s) measuredby X-ray spectroscopy. The binding energy of the O1s peak is specifiedbetween 500 eV to 550 eV. The binding energy of the C1s peak isspecified between 250 eV to 300 eV. The binding energy of the Si2p peakis specified between 80 eV to 120 eV. The binding energy of the Si2speak is specified between 130 eV to 170 eV. The binding energy of theN1s peak is specified between 375 eV to 425 eV. The binding energy ofthe Zn2p peak is specified between 1000 eV to 1050 eV. The bindingenergy of the Mg1s peak is specified between 1350 eV to 1400 eV. Thebinding energy of the Na1s peak is specified between 1050 eV to 1100 eV.The binding energy of the Fe2p3 peak is specified between 700 eV to 750eV. The binding energy of the F1s peak is specified between 650 eV to700 eV.

The silicon carbide powder according to an embodiment includes carbonand oxygen in an appropriate content ratio on the surface thereof.Accordingly, when a silicon carbide ingot and a silicon carbide wafer ismade of the silicon carbide powder according to an embodiment, defectsof the silicon carbide ingot and the silicon carbide wafer may bereduced because the content of the oxygen is appropriate.

In particular, since carbon and oxygen are included in an appropriatecontent ratio on the surface of the silicon carbide powder, the oxygenmay be easily removed by reacting with the carbon in an initial heattreatment step. Accordingly, oxygen on the surface of the siliconcarbide powder may be removed in the initial heat treatment process, anddefects in the process of growing the silicon carbide ingot may beminimized.

In addition, the oxygen is removed in the form of carbon dioxide byreacting with the carbon, and in the process of removing the oxygen, theconsumption of the carbon may be reduced. Accordingly, even after theoxygen is removed together with the carbon, the ratio of the silicon andthe carbon may be appropriate over an entirety of the silicon carbidepowder. Accordingly, the silicon carbide powder according to anembodiment may minimize defects that may occur due to non-uniformcontent of the carbon and the silicon.

In addition, the silicon carbide powder according to an embodimentincludes silicon and oxygen in an appropriate content ratio on thesurface thereof. Accordingly, the silicon carbide powder according to anembodiment may be effectively protected from external impurities. Thatis, the silicon carbide powder according to an embodiment may include anoxygen-containing protective film on the surface thereof and may beeffectively protected from external chemical impact.

In addition, the silicon carbide powder according to an embodiment mayinclude the fluorine component as a by-product in the manufacturingprocess. Here, since the method of manufacturing the silicon carbidepowder according to an embodiment includes the wet etching process, thedry etching process, and the cleaning process, the content of thefluorine component is low. In addition, since a process of manufacturinga silicon carbide ingot includes a process of heat-treating the siliconcarbide powder according to an embodiment, the fluorine component may beefficiently removed. That is, the fluorine component may be evaporatedand easily removed in the initial heat treatment process.

The silicon carbide powder according to an embodiment has a very highpurity, and by using the silicon carbide powder, a silicon carbide waferwith improved performance may be manufactured.

Referring to FIGS. 7 and 8 , the silicon carbide wafer according to anembodiment may be manufactured as follows.

First, a silicon carbide ingot may be manufactured. The silicon carbideingot is manufactured by applying a physical vapor transport method(PVT) to have a large area and few defects.

The method of manufacturing a silicon carbide ingot 12 according to anembodiment may include a preparation step, a silicon carbide powdercharging step, and a growth step.

The preparation step is a step of preparing a crucible assemblyincluding a crucible body 20 having an inner space and a crucible cover21 for covering the crucible body.

The silicon carbide powder charging step is a step of charging thesilicon carbide powder 30 in the crucible assembly and disposing a seedon the raw material at a regular interval from the raw material.

The crucible body 20 may have, for example, a cylindrical shape havingan opening with an open upper surface, wherein a silicon carbide rawmaterial can be charged in the crucible body 20. The density of thecrucible body 20 may be 1.70 g/cm³ to 1.90 g/cm³. The material of thecrucible body 20 may include graphite.

The density of the crucible cover 21 may be 1.70 g/cm³ to 1.90 g/cm³.The material of the crucible cover 21 may include graphite. The cruciblecover 21 may have a shape to cover the entire opening of the cruciblebody 20.

The crucible cover 21 may cover a portion of the opening of the cruciblebody 20 or may include a through hole (not shown). In this case, it ispossible to control the speed of vapor transport in the crystal growthatmosphere to be described below.

In addition, a seed holder 22 is disposed on the crucible cover 21. Theseed holder 22 may be coupled to the crucible cover 21. The seed holder22 may be attached to the crucible cover 21. The seed holder 22 may beintegrally formed with the crucible cover 21.

The thickness of the crucible cover 21 may be about 10 mm to about 50mm. In addition, the thickness of the seed holder 22 may be about 1 mmto about 10 mm.

To manufacture the silicon carbide ingot, a seed is prepared. The seedmay be any one of wafers to which an off angle, which is an angleselected in a range of 0 to 8 degrees with respect to the (0001) plane,is applied.

The seed may be a substantially single-crystal 4H SiC ingot with minimaldefects or polymorph incorporation. The silicon carbide seed may besubstantially made of 4H SiC.

The seed may have a diameter of 4 inches or more, 5 inches or more, andfurther 6 inches or more. More specifically, the seed may have adiameter of 4 to 12 inches, 4 to 10 inches, or 6 to 8 inches.

The seed is attached to a seed holder. The seed holder includesgraphite. The seed holder may be made of graphite. The seed holder mayinclude anisotropic graphite. In more detail, the seed holder may bemade of anisotropic graphite.

In addition, the seed and the seed holder are adhered to each other byan adhesive layer. The adhesive layer includes a graphite filler and acarbide such as a phenol resin. The adhesive layer may have a lowporosity.

The seed may be disposed such that the C surface thereof faces downward.

Next, to form the silicon carbide ingot inside the crucible, the siliconcarbide powder according to an embodiment is charged in the crucible.

The silicon carbide powder 30 includes a carbon source and a siliconsource. Specifically, the silicon carbide powder 30 includes a carbon-asilicon source. The silicon carbide powder 30 may have thecharacteristics described above. In addition, the silicon carbide powder30 may be manufactured by the methods described above.

The silicon carbide powder 30 having a particle size of 75 um or lessmay be included in an amount of 15% by weight or less, 10% by weight orless, or 5% by weight or less based on a total weight of the rawmaterial. As such, when a raw material having a relatively small contentof particles with a small particle size is applied, a silicon carbideingot that can reduce the occurrence of defects in the ingot, is moreadvantageous in controlling supersaturation, and can provide a waferwith improved crystal properties may be manufactured.

The silicon carbide powder 30 may be necked or not necked to each other.When a raw material having such a particle size is applied, it ispossible to manufacture a silicon carbide ingot that provides a waferhaving superior crystal properties.

In the silicon carbide powder charging step, the crucible assembly mayhave a weight ratio (Rw) of 1.5 to 2.7 (times) of the weight of thesilicon carbide powder when the weight of the silicon carbide powder 30is 1. Here, the weight of the crucible assembly means the weight of thecrucible assembly excluding the raw material, and specifically, means avalue obtained by excluding the weight of the inputted raw material fromthe crucible assembly including the seed regardless of whether a seedholder is applied to the crucible assembly.

When the weight ratio is less than 1.5, the degree of supersaturation inthe crystal growth atmosphere is excessively increased, and thus thecrystal quality of the ingot may be rather deteriorated. When the weightratio exceeds 2.7, the degree of supersaturation is lowered, and thusthe crystal quality of the ingot may be deteriorated.

The weight ratio may be 1.6 to 2.6 or 1.7 to 2.4. Within such a weightratio, an ingot having excellent defect characteristics or crystallinitycharacteristics can be manufactured.

In the crucible assembly, when the diameter of the inner space of thecrucible body 20 is 1, a length ratio from the lowest surface where thesilicon carbide powder 30 is located to the surface of the seed 11 maybe more than 1 times and not more than 2.5 times.

The growth step is a step of adjusting the inner space of the cruciblebody 20 to a crystal growth atmosphere so that the raw material is vaportransferred to the seed and deposited thereon, thereby preparing asilicon carbide ingot grown from the seed.

The growth step includes a process of adjusting the inner space of thecrucible assembly to a crystal growth atmosphere, and specifically, maybe carried out in a manner of wrapping the crucible assembly with aninsulating material 40 to prepare a reaction vessel (not shown)including the crucible assembly and the insulating material 40surrounding the crucible assembly and heating the crucible by a heatingmeans after placing the reaction vessel in a reaction chamber such as aquartz tube.

The reaction vessel is located in the reaction chamber 42 the innerspace of the crucible body 20 is induced to a temperature suitable forthe crystal growth atmosphere by the heating means. Such a temperatureis one of important factors in the crystal growth atmosphere, and a moresuitable crystal growth atmosphere is formed by controlling conditionssuch as pressure and gas movement. The insulating material 40 may beplaced between the reaction chamber 42 and the reaction vessel to helpthe formation and control of a crystal growth atmosphere more easily.

The insulating material 40 may affect the temperature gradient insidethe crucible body or inside the reaction vessel in the growthatmosphere. Specifically, the insulating material may include a graphiteinsulating material 40, and more specifically, the insulating material40 may include rayon-based graphite felt or pitch-based graphite felt.

As an embodiment, the insulating material 40 may have a density of about0.12 g/cc to about 0.30 g/cc. As an embodiment, the insulating material40 may have a density of about 0.13 g/cc to about 0.25 g/cc. As anembodiment, the insulating material 40 may have a density of about 0.14g/cc to about 0.20 g/cc.

When the insulating material 40 having a density of less than about 0.14g/cc is applied, the shape of a grown ingot may be concave, and 6H-SiCpolymorphism may occur, resulting in poor quality of the ingot.

When the insulating material 40 having a density of greater than about0.30 g/cc is applied, a grown ingot may be excessively convex, and agrowth rate of the edge may be lowered to decrease the yield or increasethe occurrence of cracks in the ingot.

When the insulating material 40 having a density of about 0.12 g/cc toabout 0.30 g/cc is applied, the quality of an ingot may be improved.When the insulating material 40 having a density of about 0.14 g/cc toabout 0.20 g/cc is applied, it is possible to control the crystal growthatmosphere in the ingot growth process and to grow an ingot of betterquality.

The insulating material 40 may have a porosity of about 73 vol % toabout 95 vol %. The insulating material 40 may have a porosity of about76 vol % to about 93 vol %. The insulating material 40 may have aporosity of 81 vol % to 91 vol %. When the insulating material 40 havingsuch a porosity is applied, the frequency of ingot cracking may befurther reduced.

The insulating material 40 may have a compressive strength of about 0.21Mpa or more. The insulating material 40 may have a compressive strengthof about 0.49 Mpa or more. The insulating material 40 may have acompressive strength of about 0.78 MPa or more. In addition, theinsulating material 40 may have a compressive strength of about 3 MPa orless or about 25 MPa or less. When the insulating material 40 has such acompressive strength, thermal/mechanical stability is excellent and theprobability of ash generation is low, so that a SiC ingot of betterquality may be manufactured.

The insulating material 40 may be applied to a thickness of about 20 mmor more, or may be applied to a thickness of about 30 mm or more. Inaddition, the insulating material 40 may be applied to a thickness ofabout 150 mm or less, may be applied to a thickness of about 120 mm orless, or may be applied to a thickness of about 80 mm or less. When theinsulating material 40 is applied to such a thickness range, theinsulating effect may be sufficiently obtained without unnecessary wasteof the insulating material 40.

The insulating material 40 may have a density of about 0.12 g/cc toabout 0.30 g/cc. The insulating material 40 may have a porosity of about72 vol % to about 90 vol %. When such an insulating material 40 isapplied, the shape of an ingot may be suppressed from growing concave orexcessively convex, and the deterioration of polymorphic quality and theoccurrence of cracks in the ingot may be reduced.

The crystal growth atmosphere may be realized by heating the heatingmeans 50 outside the reaction chamber 42. Simultaneously with orseparately from the heating, air is removed by decompression, and areduced pressure atmosphere and/or an inert atmosphere (e.g., Aratmosphere, N2 atmosphere, or a mixed atmosphere thereof) may be used.

The crystal growth atmosphere induces the growth of silicon carbidecrystals by vapor transporting the raw material to the surface of theseed to grow into the ingot 12.

In the crystal growth atmosphere, a growth temperature of 2100° C. to2450° C. and a growth pressure condition of 1 torr to 100 torr may beapplied, and when these temperatures and pressures are applied, asilicon carbide ingot may be manufactured more efficiently.

Specifically, to the crystal growth atmosphere, conditions of a crucibleupper and lower-surface temperature, i.e., a growth temperature, of2100° C. to 2450° C. and a growth pressure of 1 torr to 50 torr may beapplied, and more specifically, conditions of a crucible upper andlower-surface temperature, a growth temperature, of 2150° C. to 2450° C.and a growth pressure of 1 torr to 40 torr may be applied.

More specifically, conditions of a crucible upper and lower-surfacetemperature, i.e., a growth temperature, of 2150 to 2350° C. and agrowth pressure of 1 torr to 30 torr may be applied.

When the above-described crystal growth atmosphere is applied, a siliconcarbide ingot of a higher quality may be more advantageouslymanufactured by the manufacturing method of the present invention.

The silicon carbide ingot 12 contains 4H SiC and may have a convex orflat surface.

When the surface of the silicon carbide ingot 12 is formed in a concaveshape, other polymorphs such as 6H-SiC may be mixed in addition to theintended 4H-SiC crystal, which may degrade the quality of the siliconcarbide ingot. In addition, when the surface of the silicon carbideingot is formed in an excessively convex shape, cracks may occur in theingot itself, or crystals may be broken when processing into a wafer.

Here, whether the silicon carbide ingot 12 is an excessively convexingot is determined based on the degree of curvature, and the curvatureof the silicon carbide ingot manufactured according to the presentspecification is about 20 mm or less.

The curvature is evaluated as a value of (center height−edge height) byplacing a sample, on which the growth of a silicon carbide ingot iscompleted, on a surface plate and measuring the height of the center ofthe ingot and the height of the edge of the ingot with a height gaugebased on the rear surface of the ingot. In the curvature value, apositive value means convexity, 0 means flatness, and a negative valuemeans concave.

Specifically, the surface of the silicon carbide ingot 12 may have aconvex shape or a flat shape, and the curvature of the silicon carbideingot 12 may be about 0 mm to about 14 mm, about 0 mm to about 11 mm, orabout 0 mm to about 8 mm. A silicon carbide ingot having such acurvature degree may make wafer processing easier and reduce cracking.

The silicon carbide ingot 12 may be a substantially monocrystal 4H SiCingot with minimal defects or polymorph incorporation. The siliconcarbide ingot 12 is substantially made of 4H SiC, and the surfacethereof may have a convex shape or a flat shape.

The silicon carbide ingot 12 may reduce defects that may occur in asilicon carbide ingot and may provide a silicon carbide wafer withhigher quality.

In the case of the silicon carbide ingot manufactured by the method ofthe present specification, pits on the surface of the silicon carbideingot may be reduced. Specifically, in an ingot having a diameter of 4inches or more, pits included in the surface thereof may be about 10k/cm² or less.

In the present specification, for the surface pit measurement of thesilicon carbide ingot, a total of 5 position including one position ofthe central part, except for the facet, on the ingot surface and 3o'clock, 6 o'clock, 9 o'clock, and 12 o'clock positions located withinabout 10 mm from the edge of the silicon carbide ingot toward the centeris observed with an optical microscope, pits per unit area (1 cm2) ateach location are measured, and an average value of the pits is used forevaluation.

For example, the outer edge of the silicon carbide ingot is trimmedusing external grinding equipment (external grinding) and, after cuttingto a certain thickness (slicing), processing such as edge grinding,surface grinding, or polishing may be carried out.

The slicing step is a step of preparing a sliced crystal by slicing asilicon carbide ingot to have a certain off-angle. The off-angle isbased on the (0001) plane in 4H SiC. Specifically, the off-angle may bean angle selected from 0 to 15, may be an angle selected from 0 to 12,or may be an angle selected from 0 to 8.

The slicing is not specifically limited so long as it is a slicingmethod that is generally applied to wafer manufacturing, and forexample, cutting using a diamond wire or a wire to which a diamondslurry is applied, cutting using a blade or wheel to which diamond ispartially applied, etc. may be applied, without being limited thereto.

The thickness of the sliced crystal may be adjusted in consideration ofthe thickness of the wafer to be manufactured, and may be sliced to anappropriate thickness in consideration of the thickness after beingpolished in a polishing step to be described below.

In addition, the slicing starts at a place about 3° away from the pointwhere the outer circumferential surface of the silicon carbide ingot andthe second direction meet, and proceeds in the second direction. Thatis, the direction in which the slicing proceeds may be a directiondeviated by about 3° from the second direction. That is, the movementdirection of the sawing wire for the slicing may be a direction inclinedby about 3° from a direction perpendicular to the second direction. Thatis, the extension direction of the sawing wire is a direction inclinedby about 3° from a direction perpendicular to the second direction, andthe silicon carbide ingot may be gradually trimmed and cut in adirection inclined by about 3° from the second direction.

Accordingly, in the slicing process, the occurrence of stress in thefirst direction may be minimized. That is, in the slicing process, sinceno pressure is applied in the first direction in the slicing process,the stress in the first direction may be minimized, and the deviation ofthe peak omega angle in the first direction may be minimized.

The polishing step is a step of polishing the sliced crystal to athickness of 300 to 800 um to form a silicon carbide wafer.

In the polishing step, a polishing method commonly applied to wafermanufacturing may be applied, and, for example, after a process such aslapping and/or grinding is performed, polishing, etc. may be applied.

The silicon carbide wafer according to an embodiment may have a lowsurface oxygen concentration. In the silicon carbide wafer according toan embodiment, the surface oxygen concentration measured by the X-rayphotoelectron spectroscopy may be about 5 atom % to about 14 atom %. Inthe silicon carbide wafer according to an embodiment, the surface oxygenconcentration measured by the X-ray photoelectron spectroscopy may beabout 6 atom % to about 13 atom %. In the silicon carbide waferaccording to an embodiment, the surface oxygen concentration measured bythe X-ray photoelectron spectroscopy may be about 7 atom % to about 12.5atom %. In the silicon carbide wafer according to an embodiment, thesurface oxygen concentration measured by the X-ray photoelectronspectroscopy may be about 8 atom % to about 12 atom %.

Accordingly, since the silicon carbide wafer according to the embodimenthas a low surface oxygen content, a high yield may be realized when usedin a manufacturing process of a power semiconductor device. The siliconcarbide wafer according to the embodiment may have a yield of about 88%or more with respect to a manufactured power semiconductor device. Thatis, the method of manufacturing a power semiconductor device using asilicon carbide wafer according to the embodiment may provide a yield ofabout 88% or more.

Hereinafter, the present invention will be described in detail throughspecific examples. The following examples are provided only to help theunderstanding of embodiments, and the scope of the invention disclosedin the present specification is not limited thereto.

MANUFACTURING EXAMPLE 1

A monocrystal silicon carbide lump was provided as a silicon carbide rawmaterial. The monocrystal silicon carbide lump may be formed bysublimating a silicon carbide powder having a purity of about 99.9999%or more at a temperature of about 2300° C. and depositing it on a seed.

The monocrystal silicon carbide lump was first pulverized by a jawcrusher (Henan Dewo Industrial Limited Company, KER-100×60). From thepulverized silicon carbide lump, a primary powder having a particlediameter of about 1 mm to about 6 mm was obtained.

Next, the primary powder was secondarily pulverized by a ball mill(Ganzhou Li Ang Machinery Co., Ltd., QM400*600). The secondarilypulverized primary powder was classified by a classifier, and asecondary powder having an average particle diameter (D50) of about 500μm was obtained.

Next, the secondary powder was heat-treated at a temperature of about1200° C. in an air atmosphere about 1200° C. for about 24 to remove freecarbon and free silicon.

Next, the heat-treated silicon carbide powder was purified by a wetetching process.

Deionized water, an aqueous hydrofluoric acid solution (aqueous solutionat a concentration of 30 wt %), and an aqueous nitric acid solution(aqueous solution at a concentration of 30 wt %) were mixed in a weightratio of about 3:1.5:1.5, thereby manufacturing an etchant.

Next, about 1 l (apparent volume) of the heat-treated silicon carbidepowder was fed into an etch vessel having a volume of about 5 l, andabout 0.8 l of the etchant was fed thereinto.

Next, the etch vessel was sealed with a lid. Here, oil vapor generatedin the etch vessel was discharged through the lid, and the oil vapor wasrecovered by a scrubber.

The etchant and the heat-treated silicon carbide powder were stirred ata speed of about 26 rpm for about 1 hour.

Next, the etchant was drained, and the wet-etched silicon carbide powderwas neutralized with deionized water by the following process. Thewet-etched silicon carbide powder was immersed in deionized water, andafter stirring, the deionized water was discharged. This immersion anddischarge process was repeated until the pH of the discharged deionizedwater reached 7.

Next, the neutralized silicon carbide powder was dried at about 80° C.for about 30 minutes.

Next, the dried silicon carbide powder was placed in a graphitecrucible.

Next, the internal temperature of the crucible was increased up to about2000° C., and the inside of the crucible was depressurized to a pressureof about 8 torr.

Next, an etching gas in which argon and chlorine gas were mixed in avolume ratio of about 10:1 was introduced into the crucible, and thepressure inside the crucible was increased to about 760 torr. Here, thetemperature of the crucible was set so that the temperature of the lowerpart of the crucible was about 50° C. higher than the temperature of theupper part of the crucible. This state was maintained for about 2 days.

Next, the etching gas inside the crucible was recovered by a scrubber,and the inside of the crucible in which the dry-etched silicon carbidepowder was disposed was heat-treated at about 1000° C. in an airatmosphere for about 10 hours.

Next, the heat-treated silicon carbide powder was immersed in an aqueoushydrofluoric acid solution at a concentration of about 0.5 wt %, and thesilicon carbide powder and the aqueous hydrofluoric acid solution werestirred for about 1 hour.

Next, the silicon carbide powder treated with the aqueous hydrofluoricacid solution was immersed in ultrapure water and thoroughly mixed, andthe ultrapure water was drained. This process was repeated. Here, theimmersion and drainage processes were repeated until the concentrationof hydrofluoric acid contained in the drained ultrapure water waslowered to about 0.0001 wt % or less.

MANUFACTURING EXAMPLES 2 TO 4

Manufacturing Examples 2 to 4 were substantially the same asManufacturing Example 1, and etchants and etching gases summarized inTables 1 and 2 below were used.

TABLE 1 50 wt % aqueous 30 wt % aqueous Deionized water hydrofluoricnitric acid (parts acid solution solution Classification by weight)(parts by weight) (parts by weight) Manufacturing 3 1.5 1.5 Example 1Manufacturing 3 1 1 Example 2 Manufacturing 3 1 1 Example 3Manufacturing 3 1.5 1.5 Example 4

TABLE 2 Classification Argon (sccm) Chlorine gas (sccm) Manufacturing100 10 Example 1 Manufacturing 100 50 Example 2 Manufacturing 100 100Example 3 Manufacturing 100 100 Example 4

EXAMPLE

Next, the silicon carbide powder produced in Manufacturing Example 1 wascharged into a graphite crucible body. A silicon carbide seed and a seedholder were placed on the powder. Here, the C surface (0001) of thesilicon carbide seed crystal was fixed in a conventional manner to facethe lower part of the crucible. In addition, a crucible cover and a seedholder were integrally manufactured with graphite, and both the cruciblecover and the seed crystal holder had a disk shape. Here, the thicknessof the crucible cover was about 20 mm, the diameter of the cruciblecover was about 210 mm, the thickness of the seed holder was about 3 mm,and the diameter of the seed holder was about 180 mm.

The main body of the crucible was covered with the crucible cover inwhich the seed and the seed holder were installed, surrounded by a heatinsulating material 40, and placed in a reaction chamber provided with aheating coil as a heating means.

Here, graphite felt having a density of about 0.19 g/cc, a porosity ofabout 85 vol %, and a compressive strength of about 0.37 MPa was appliedas an insulation material.

After making the inside of the crucible in a vacuum state, argon gas wasslowly injected thereinto so that the inside of the crucible reachedatmospheric pressure. The inside of the crucible was graduallydecompressed again. At the same time, the temperature inside thecrucible was gradually increased to 2000° C. at a temperature increaserate of about 3° C./min, and then gradually increased to 2350° C. at atemperature increase rate of about 5° C./min.

Next, a SiC ingot was grown from a silicon carbide seed for 100 hoursunder conditions of a temperature of 2350° C. and a pressure of 20 torr.

Next, the silicon carbide ingot was cut by a diamond wire saw, andprocessed by a chamfering process, a grinding process, and a grindingprocess. Accordingly, a silicon carbide wafer having an off angle of 4degrees with respect to the (0001) plane was manufactured.

EXAMPLES 2 TO 4 AND COMPARATIVE EXAMPLES 1 AND 2

As summarized in Table 3 below, the same process as in Example 1 wascarried out except that the silicon carbide powder was changed.

TABLE 3 Classification Silicon carbide powder Example 1 ManufacturingExample 1 Example 2 Manufacturing Example 2 Example 3 ManufacturingExample 3 Example 4 Manufacturing Example 4 Comparative Carborexmanufactured by Washington Mills Example 1 Comparative Green SiliconCarbide manufactured by Pacific Rundum Example 2

MEASUREMENT EXAMPLE

1. Silicon Carbide Powder Purity

The purity of the silicon carbide powder according to the manufacturingexample was measured by glow discharge mass spectrometry.

2. Silicon Carbide Powder Shape

The silicon carbide powder manufactured in the manufacturing example wasphotographed with an optical microscope (Eclipse LV150 Microscope,manufactured by Nikon), and analyzed by an image analysis program(i-solution, manufactured by IMT).

3. XPS Analysis

XPS equipment name/manufacturer: K-Alpha+/ThermoFisher Scientific

Measurement Conditions

1) X-ray source: Monochromated Al X-Ray sources (Al Kα line: 1486.6 eV)

2) X-Ray power: 12 kV, 10 mA

3) Sampling area: 400 um (diameter)

4) Narrow scan: pass energy 40 eV, step size 0.05 eV

5) Vacuum: 3×10⁻⁹ mbar

6) Calibration: No

7) Flood gun is used for charge compensation ON

<Etching Conditions>

Ar Ion etching: 2 keV, 1500 sec, raster size: 2×2 mm

4. Wafer Surface Oxygen Concentration

The oxygen concentration on the surface of the manufactured wafer wasmeasured in the same manner as in the XPS analysis.

5. Wafer Fabrication Device Yield

An epitaxial layer having a thickness of about 10 μm was formed on eachof the silicon carbide wafers prepared in the examples and thecomparative examples. Next, about 3922 power semiconductor devices wereformed, and it was checked whether each power semiconductor device wasdefective.

TABLE 4 Oxygen Surface oxygen concentration concentration at etchingtime (atom %) of from 100 seconds Purity silicon carbide to 800 secondsClassification (%) powder (atom %) Example 1 99.9999 or more 8.90 2.81to 3.10 Example 2 99.9999 or more 8.95 2.86 to 3.16 Example 3 99.9999 ormore 8.93 2.82 to 3.11 Example 4 99.9999 or more 8.89 2.80 to 3.05Comparative 99.9% 13.49 3.17 to 3.64 Example 1 Comparative 99.9% 22.353.21 to 3.75 Example 2

TABLE 5 Classification O1s/C1s O1s/Si2p N1s/C1s Zn2p/C1s Mg1s/C1sExample 1 0.2116 0.3813 0.0091 0.0226 0.0024 Example 2 0.2378 0.2940.0169 0.0087 0.0048 Example 3 0.2234 0.3517 0.0085 0.0102 0.0033Example 4 0.2278 0.3656 0.0103 0.0094 0.0042 Comparative 0.3993 0.51790.0300 0.0641 0.0153 Example 1 Comparative 0.2991 0.3983 0.0194 0.00320.0135 Example 2

TABLE 6 Oxygen concentration Power semiconductor (atom %) in deviceyield Classification wafer surface (%) Example 1 11.66 91 Example 211.38 90 Example 3 11.56 91 Example 4 11.49 90 Comparative 17.12 87Example 1 Comparative 14.31 85 Example 2

As summarized in Tables 4 to 6, the silicon carbide powders produced bythe examples have an appropriate oxygen concentration at the surface andpredetermined depth thereof. In addition, the silicon carbide wafersmanufactured according to the examples have an appropriate surfaceoxygen concentration and an improved power semiconductor device yield.

DESCRIPTION OF SYMBOLS

seed 11

silicon carbide ingot 12

crucible body 20

crucible cover 21

seed holder 22

silicon carbide powder 30

reaction chamber 42

an insulating material 40

heating means 50

1. A silicon carbide powder, comprising carbon and silicon, whereinO1s/C1s measured by X-ray photoelectron spectroscopy is 0.28 or less. 2.The silicon carbide powder according to claim 1, wherein O1s/Si2p of asurface measured by X-ray photoelectron spectroscopy is 0.39 or less. 3.The silicon carbide powder according to claim 2, wherein an oxygen ratioin the surface measured by X-ray photoelectron spectroscopy is 13 atom %or less.
 4. The silicon carbide powder according to claim 3, whereinN1s/C1s of the surface measured by X-ray photoelectron spectroscopy is0.018 or less.
 5. The silicon carbide powder according to claim 4,wherein a concentration of oxygen in a depth where an oxygenconcentration change according to an etching time is 2 atom %/100 s orless is 5 atom % or less.
 6. The silicon carbide powder according toclaim 1, wherein Zn2p/C1s of a surface of measured by X-rayphotoelectron spectroscopy is 0.023 or less.
 7. The silicon carbidepowder according to claim 6, wherein Mg1s/C1s of the surface of thesilicon carbide powder measured by X-ray photoelectron spectroscopy is0.005 or less.
 8. A method of manufacturing a silicon carbide powder,the method comprising: providing a raw material containing siliconcarbide; pulverizing the raw material; and removing an impurity includedin the raw material, wherein O1s/C1s of a surface measured by X-rayphotoelectron spectroscopy is 0.28 or less.
 9. The method according toclaim 8, wherein the removing comprises etching a surface of the rawmaterial.
 10. The method according to claim 9, wherein in the etching,an etchant comprising hydrofluoric acid and nitric acid is used.
 11. Asilicon carbide wafer, comprising a Si surface and C surface opposite toeach other, wherein a ratio of oxygen measured by X-ray photoelectronspectroscopy in the Si surface is 14 atom % or less.